149670-99-5Relevant academic research and scientific papers
Molecular solid-gas organometallic chemistry. Catalytic and stoichiometric transformations of ethyne at iridium
Bianchini, Claudio,Frediani, Piero,Graziani, Mauro,Kaspar, Jan,Meli, Andrea,Peruzzini, Maurizio,Vizza, Francesco
, p. 2886 - 2887 (1993)
The η2-ethene dihydride [(triphos)Ir(H)2-(C2H4)]BPh4 (1; triphos = MeC(CH2PPh2)3) reacts in the solid state with ethyne (4 atm) at 70°C to give five different organome
Mechanistic study of Ir(H)2-assisted transformations of ethyne: Cyclotrimerization, cooligomerization with ethene, and reductive coupling
Bianchini, Claudio,Caulton, Kenneth G.,Johnson, Todd J.,Meli, Andrea,Peruzzini, Maurizio,Vizza, Francesco
, p. 933 - 943 (2008/10/09)
The (ethene)dihydride complex [(triphos)Ir(H)2(C2H4)]BPh4 (1) is capable of promoting a variety of transformations of ethyne, including cyclotrimerization to benzene, cooligomerization with ethene to hexa-1,3,5-triene, reductive coupling to buta-1,3-diene, and hydrogenation to ethene (triphos = MeC(CH2PPh2)3). A detailed study under various experimental conditions, the detection of several intermediates along the various reaction paths, and the use of isolated complexes in independent reactions, taken together, permit mechanistic conclusions that account for the varied products. In particular, the cyclotrimerization and cooligomerization reactions are mediated by an iridacyclopentadiene species which is trapped by either ethyne or ethene. Consumption of the hydride ligands of 1 by C2H2 or C2H4 is an ingredient for both cyclotrimerization and cooligomerization reactions but is not necessary to accomplish the reductive dimerization of ethyne to buta-1,3-diene for which, conversely, the two hydride ligands are mandatory.
Molecular solid-gas organometallic chemistry. Catalytic and stoichiometric iridium-assisted C-C bond-forming reactions involving ethyne and ethene
Bianchini, Claudio,Graziani, Mauro,Kaspar, Jan,Meli, Andrea,Vizza, Francesco
, p. 1165 - 1173 (2008/10/08)
Treatment of crystals of the (η2-ethene)dihydride complex [(triphos)Ir(H)2(C2H4)]BPh4 (1; triphos = MeC(CH2PPh2)3) with ethyne (4 atm) at 70°C for 3 h results in evolution of ethene and but-2-ene and formation of five different organometallic products, namely the η4-benzene complex [(triphos)Ir(η4-C6H6)]BPh4 (2), the η4-buta-1,3-diene complex [(triphos)Ir(η4-C4H6)]BPh4 (3), the η4-cyclohexa-1,3-diene complex [(triphos)Ir(η4-C6H8)]BPh4 (4), and the crotyl hydride isomers [(triphos)Ir(H)(η3-MeC3H4)]BPh4 (5-anti and 5-syn) in a kinetic product ratio of 35:5:23:28:9. At 100°C, the solid-gas reaction produces catalytic amounts of benzene, the catalyst precursor being the η4-benzene complex 2. Temperature-programmed reactions carried out in a flow reactor and the use of isolated complexes in independent solid-gas reactions permit mechanistic conclusions which account for the varied organic and organometallic products. The ethene ligand in 1 is an essential ingredient for both cyclotrimerization and cooligomerization reactions of ethyne, which are traversed by η3-crotyl complexes. Conversely, the ethene ligand is a competitive inhibitor for the reductive dimerization of ethyne to buta-1,3-diene, for which the two hydride ligands are mandatory. Comparison with fluid solution-phase systems provides evidence for the control exerted by the constraining environment of the crystal lattice on the solid-gas reactions.
